The Stellar interview is set to show a more revealing side to the TODAY star when it hits newsstands Sunday.

"I've had some very dark moments where I've felt ashamed and that I had failed," a quote from Karl reads on the cover.

The father-of-three made his official romantic debut with 33-year-old former model Jasmine Yarbrough at Mercedes Benz Fashion Week in March, before finalising his divorce from his wife of 21 years,Cassandra Thornburn, in May.

Since then, the pair have been spotted out and about in Sydney, even jetting off for a romantic getaway in Bora Bora.

It's a big year for Karl. A trailer was released on Friday for his brand new Nine show, This Time Next Year. The program will document everyday Australians as they attempt to tackle monumental personal goals during the most challenging year of their life.

However, the host has revealed not all the contestants had positive results:

"Some contributors were successful, some weren't. But they all have an amazing story to share," he said in a statement.

"Even I wasn't aware of the outcome until I met them back on stage. This Time Next Year is a show I'm proud to be a part of."

In the premiere episode, we will meet Sequoiah and Luke, a young couple from Gawler in South Australia who are determined to have a baby despite difficulties conceiving and several failed attempts at IVF.